That was the topic of a panel at the Association of the US Army (AUSA) conference this week, the heavily attended annual trade show that draws top Pentagon officials and defense contractors.

It's a tricky proposition for the Pentagon, since making the wrong predictions means squandering scarce funds in a time of intense budget pressure. The Pentagon was forced to cancel the Future Combat System in 2009, for example, when the military tried to predict where the future was headed "more than a few years out," said Gen. Robert Cone, head of the US training and doctrine command. As a result, he told the panel, "We're a little gun-shy."

Still, in a standing-room-only session, the discussion endeavored to come up with the most likely risks to the stability of the world – and most likely to challenge the US military – in 2030 and beyond. Here are their top three picks.

ByAnna Mulrine, Staff writerOctober 24, 2013

1.
The growth of cities – and of slums

Police officers patrol the Lins slum complex during an operation to install a Pacifying Police Unit in Rio de Janeiro on Oct. 6. The action is part of a policing program aiming to drive violent and heavily armed drug gangs out of Rio's slums, where the traffickers have ruled for decades.

Silvia Izquierdo/AP

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By 2040, an estimated 65 percent of the world’s population will be in cities. That’s 6 billion people. While overall poverty will decline, an estimated one-third of those people – or 2 billion – will be living in a “slumlike situation,” says Kathleen Hicks, who was until August the Pentagon’s principal deputy undersecretary of Defense for policy.

This in turn will result in a “very high potential for lack of governance.”

With cities growing quickly, “You just don’t have the governance structures to keep up with that,” she adds, noting that services like sanitation and local trash collection could fall by the wayside and create grievances.

Such a “hyper-pressurized, compact environment” could fuel criminal organizations, much like the narco-gangs of Central America.

It could also create alternative means of governance, such as Hamas-like organizations, to meet the daily needs of the people.